Experimental Study On Mechanical Properties And Bond Behavior Of Fiber-Reinforced High Strength Lightweight Aggregate Concrete

High-strength lightweight concrete(HSLC)which has light weight,high-strength,high durability,good fire resistance,is a kind of green building materials with good application prospect.However,when damaged,HSLC features aggregate damage,which is under the category of brittle failure.Therefore,the poor ductility and low strength as structural material has limited the wide application of HSLC.With the advancement of aggregate and cement production technique as well as the mix of fiber,the strength and toughness of HSLC has seen effective improvement.But there still exists disputes concerning bond behavior due to the lack of related researches.Based on the mixture of HSLC,the research aims at improving its strength and toughness and get high performance.Researches have been made over the mechanical properties and fiber effect microscopically and macroscopically.The bond behavior of HSLC and steel fiber was also studied.The main contents are:1.To study their mechanical properties,LC40~LC60 concrete were prepared.Carbon fiber and steel fiber as well as glass fiber were mixed with the concrete so as to improve its toughness.The results showed that compressive strength tended to rise when dry density increased or water-binder ratio decreased.The concrete strength increased obviously when adding silica fume.Both the toughness and strength could be improved if adding fiber.Besides,adding carbon fiber works more effective in improving properties than steel fiber.2.6 groups of microscopic specimens were designed and S-4800 scanning electron microscope was used so as to study the interfacial zone.The results showed that the bond behavior of HSLC is better than ordinary concrete.Adding silica fume could improve the interfacial zone.Carbon fiber could increase the density of matrix and restrain the spread of fissure.Under the same volume fraction,carbon fiber functions better in improving the toughness and strength compared with steel fiber.3.17 pull-out bond test pieces and 4 inner-embedded strain-gauges test pieces were designed.Studies were made over the bond behavior and bond stress-slip constitutive model of HSLC and steel.The results showed that strength grade of HSLC,the type of fiber,bond length and the type of aggregate could affect the bond behavior while the diameter of steel affects little.The basic ?-s relationship model and bond position function of the whole process of bonding-slip relationship curve were made.The basic ?-s relationship model and bond position function of bonding-slip relationship curve of carbon fiber and steel fiber after bond behavior were also made.Besides,bond stress-slip constitutive model was made.The researches about the HSLC's physical properties,modification,fiber effect,microstructure and bond behavior have significant theory and application value in mastering the properties,instructing engineering design and promoting application.